Audio recording systems can make use of more than one microphone to pick-up and record audio in the surrounding environment. Mobile devices increasingly have several microphones. The microphones are used for many applications like surround sound (such as 5.1 channel) capture and noise cancellation. Many signal processing algorithms for multiple microphones require the microphones to be well calibrated in relation to each other. Also, many algorithms need as close to as possible free-field conditions to work well. However, the mobile device itself shadows sounds coming from certain directions to a microphone. The shadowing effect is different for microphones placed to different parts of the device. However, there usually are some directions from which the shadowing effect is the same for 2 or more microphones.
Furthermore occasionally the operation of one or more of these microphones may become impaired. For example, a microphone may become blocked, partially blocked, broken or otherwise impaired in operation.
For example, small particles such as dust may become embedded in the microphone leading to a deterioration in the operation of the microphone, a microphone may become blocked or partially blocked by a finger or other body part, a microphone may break or partially break due to a mechanical or other cause and/or a microphone may become impaired due to sound distortion introduced by environmental factors such as wind.
This may lead to a reduction in the quality of the recorded audio.